In the Battletech (fictional) universe, giant robots are built using actual human muscle tissue. According to their logic, all other methods simply yielded engines and motors that were unable to actually apply enough force to control the arms and legs. I remember thinking "That's the dumbest thing I've ever heard."

Someone's actually done it. Not build giant robots, but rather to artificially grow muscle tissue on a robot and use the muscle tissue to manipulate joints. I think this is really cool, and I can say this without being self contradicting because what I thought was dumb was the idea that muscle tissue was the only strong enough way, not the idea of using muscle tissue itself. The researchers used a gold ribbon to guide the muscle growth. Rather than just having a mass of cells grow randomly into a blob, the cells for some reason grow along the ribbon to give the cells the stringiness that make them muscles. Or something. IANA Biologist. This, coupled with DNA computers, paints a somewhat scary image of artificial biological machines. Sci-fi has typically portrayed the future as being made up mostly of sterilized white plastic (think Star Wars Stormtrooper armor). Will the next trend in sci-fi be an organic future (think StarCraft Zergs)?